Robotic work tool system and a charging connector arrangement for a robotic work tool system

ABSTRACT

A robotic work tool system, comprising a charging station and a robotic work tool, said robotic work tool comprising two charging connectors arranged on an upper side of the robotic work tool and said charging station comprising two charging connectors and a supporting structure arranged to carry said charging connectors and to extend over and above said robotic work tool as the robotic work tool enters the charging station for establishing electrical contact between the charging connectors of the robotic work tool and the charging connectors of the charging station from above, wherein said supporting structure is arranged to allow the robotic work tool exit the charging station by driving through the charging station without reversing.

TECHNICAL FIELD

This application relates to a robotic work tool system for improvedcharging, and in particular to a robotic work tool system for improvedcharging while ensuring a safe operation and for minimizing the wear andtear of a work area in which the robotic work tool is to operate within.

BACKGROUND

Many contemporary robotic working tools, such as robotic lawnmowers, aredesigned to work in a work area defined by a boundary, for examplethrough the use of a boundary wire. Electrical robotic work toolsoperate inside the working area and are driven by battery power. Torecharge the batteries of the robotic work tool a charging station isused that the robotic work tool enters when the battery power dropsbelow a certain level or when an operating program, such as a mowingprogram, is finished. Alternatively, the robotic work tool is propelledusing a combustion engine, in such an alternative, the robotic work toolis configured to enter a service station for example for taking onadditional fuel.

Traditionally, robotic work tools are of a relatively small size so thatthey are suitable for operating in a private sphere such as in a home oran office for robotic work tools such as vacuum cleaners or a garden forlawnmower robots. The charging stations for such traditional roboticwork tools are of a drive-in model where the robotic work tool entersthe charging station from the front, makes contact with chargingcontacts or other power transferring means, and, when fully charged,reverses out of the charging station to continue operation.

As technology evolves more and more advanced uses are becoming availablefor robotic work tools. Examples of such more advanced uses arelawnmowers with a greater capability for mowing larger areas and farmingequipment which are being made possible by evolved battery andelectrical motor technology. These robotic work tools are of a largersize and also often prone to more wear and tear and rougher operatingconditions. In one instance the rougher operating conditions are aresult of the operating area being larger and the operating excursion ofa longer duration under which the robotic work tool is subjected to moredirt and other environmental factors, wind, blowing debris etc.

Traditional servicing stations (such as charging stations or fuellingstations) are not suitable for such evolved robotic work tools in thatthe construction of the charging station becomes too heavy. Traditionalservicing stations also block the travel path of a robotic work toolthat may be unable to reverse. The traditional charging stations arethus limiting with regards to for example placement.

Furthermore, traditional service stations also suffer from lawn wearbeing caused in the area surrounding the service station by the roboticwork tool as it attempts to align with and dock with the servicestation.

Traditional service stations also require more time and effort to bealigned with.

There is thus a need for a robotic work tool system adapted for morecomplicated robotic work tools

SUMMARY

It is an object of the teachings of this application to overcome theproblems listed above by providing a robotic work tool system,comprising a charging station and a robotic work tool, said robotic worktool comprising two charging connectors arranged on an upper side of therobotic work tool and said charging station comprising two chargingconnectors and a supporting structure arranged to carry said chargingconnectors and to extend over said robotic work tool as the robotic worktool enters the charging station for establishing electrical contactbetween the charging connectors of the robotic work tool and thecharging connectors of the charging station from above, wherein saidsupporting structure is arranged to allow the robotic work tool exit thecharging station by driving through the charging station withoutreversing.

This enables the charging station to be used with two-part models, suchas articulated models, as well as one-part models and it also reducesthe tracks and lawn-wear in the area surrounding the charging station.It also reduces the size necessary for the charging station as thecharging connectors only need to be carried on a small supportingstructure extending over the robotic work tool. As the robotic work toolis supposed to drive through the charging station, the supportingstructure may not block the travel path of the robotic work tool.

In on embodiment the charging connectors of the robotic work tool arearranged in series. This further reduces the size necessary for thesupporting structure, making the charging station even smaller.

In on embodiment the charging connectors of the robotic work tool arearranged on one side of the upper side of the robotic work tool withregards to the direction of movement of the robotic work tool. Thisfurther decreases the necessary size of the supporting structure.

A smaller structure is also easier to make in a strong and robust mannerwith out affecting the weight so that the arrangement would be difficultto transport or install.

The extending structure also enables for an easy addition of a roof orother superstructure. The extending structure coupled with a cover orroof thereby enables the charging station to protect components that aresensitive to wear and tear and other influences from the environment.

In one embodiment the charging connector of the charging station isarranged as a collector shoe gear. This enables the charging connectorsto clean each other by scraping of dirt. It also allows for variance inthe height of the robotic work tool to be charged.

Further benefits of the teachings herein include, but are not limitedto, that the charging connector arrangement is arranged to provide aconstant contact pressure independent of the height, tilt and sidewaysposition of the robotic wok tool and the service station is able toreceive a robotic work tool in either direction. The charging stationaccording to herein is thus arranged to accept and cope with variancesin sideways position and sideways tilting of a robotic work tool to beserviced.

The robotic work tool and the charging station according to theteachings herein is thus suitable for operation in dirty and roughenvironments and will be able to function even after being subjected towear and tear such as being covered in dirt and/or slightly rusted,situations in which rolling wheel contacts may not be able to functioncorrectly.

In one embodiment the robotic work tool is a robotic lawnmower. In oneembodiment the robotic work tool 100 is a farming equipment. In oneembodiment the robotic work tool 100 is a golf ball collecting tool. Therobotic work tool 100 may also be a vacuum cleaner, a floor cleaner, astreet sweeper, a snow removal tool, a mine clearance robot or any otherrobotic work tool that is required to operate in a work area in amethodical and systematic or position oriented manner.

The inventors of the present invention have realized, after inventiveand insightful reasoning that by providing for a drive-througharrangement the supporting structure may be made sufficiently small tobe easy to transport.

Furthermore, the use of connector rails and sliding contacts provide foran easy to maintain system which is robust and also accommodates forvariance in heights of robotic work tools to be charged.

It is an object of the teachings of this application to overcome theproblems listed above by providing a charging connector arrangement fora robotic work tool system comprising a robotic work tool and a chargingstation, said charging connector arrangement comprising a rail connectorarranged on said robotic work tool and a mating charging connectorarranged on said charging station, said mating charging connector beingmovably connected to said charging station through a lever arrangementto enable a reduced friction and reducing an impact when said roboticwork tool enters said charging station and said mating chargingconnector makes contact with said connector rail.

It is an object of the teachings of this application to overcome theproblems listed above by providing a service station is provided, saidservice station robotic work tool system, comprising a service stationand a robotic work tool, said robotic work tool comprising at least onecorresponding connector arranged on an upper side of the robotic worktool and said service station comprising at least one mating connectorand a supporting structure arranged to carry said at least one matingconnector and to extend over said robotic work tool as the robotic worktool enters the service station for establishing an energy transfercontact between the at least one corresponding connector of the roboticwork tool and the at least one mating connector of the service stationfrom above, wherein said supporting structure is arranged to allow therobotic work tool to exit the service station by driving through thecharging station.

Other features and advantages of the disclosed embodiments will appearfrom the following detailed disclosure, from the attached dependentclaims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted accordingto their ordinary meaning in the technical field, unless explicitlydefined otherwise herein. All references to “a/an/the [element, device,component, means, step, etc.]” are to be interpreted openly as referringto at least one instance of the element, device, component, means, step,etc., unless explicitly stated otherwise. The steps of any methoddisclosed herein do not have to be performed in the exact orderdisclosed, unless explicitly stated.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in further detail under reference to theaccompanying drawings in which:

FIG. 1 shows a schematic overview of a robotic work tool according toone embodiment of the teachings of this application;

FIG. 2 shows a schematic view of a robotic working tool system accordingto one embodiment of the teachings of this application;

FIG. 3 shows a schematic view of a robotic work tool system according toone embodiment of the teachings of this application;

FIG. 4 shows an enlarged sectional schematic view of a robotic work toolsystem according to one embodiment of the teachings of this application;

FIG. 5 shows an enlarged sectional schematic view of an alternativerobotic work tool system according to one embodiment of the teachings ofthis application;

FIG. 6 shows a detailed view of a robotic work tool system according toone embodiment of the teachings of this application; and

FIG. 7 shows a schematic example a service station according to oneembodiment of the teachings of this application.

DETAILED DESCRIPTION

The disclosed embodiments will now be described more fully hereinafterwith reference to the accompanying drawings, in which certainembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

FIG. 1 shows a schematic overview of a robotic work tool 100 having abody 140 and a plurality of wheels 130. In the exemplary embodiment ofFIG. 1 the robotic work tool 100 has 4 wheels 130, two front wheels 130′and the rear wheels 130″. At least some of the wheels 130 are drivablyconnected to at least one electric motor 150. It should be noted thateven if the description herein is focussed on electric motors,combustion engines may alternatively be used possibly in combinationwith an electric motor.

In the example of FIG. 1, the rear wheels 130″ are connected to each anelectric motor 150. This allows for driving the rear wheels 130″independently of one another which, for example, enables steep turning.

The robotic work tool 100 also comprises a controller 110. Thecontroller 110 may be implemented using instructions that enablehardware functionality, for example, by using executable computerprogram instructions in a general-purpose or special-purpose processorthat may be stored on a computer readable storage medium (disk, memoryetc.) 120 to be executed by such a processor. The controller 110 isconfigured to read instructions from the memory 120 and execute theseinstructions to control the operation of the robotic work tool 100. Thecontroller 110 may be implemented using any suitable, publicallyavailable processor or Programmable Logic Circuit (PLC). The memory 120may be implemented using any commonly known technology forcomputer-readable memories such as ROM, RAM, SRAM, DRAM, FLASH, DDR,SDRAM or some other memory technology.

The robotic work tool 100 further has at least one sensor 170, in theexample of FIG. 1 there are two sensors 170, arranged to detect amagnetic field (not shown). The sensors are connected to the controller110 and the controller 110 is configured to process any signals receivedfrom the sensors 170. The sensor signals may be caused by the magneticfield caused by a control signal being transmitted through a boundarywire (for more details on charging stations, control signals andboundary wires, see the description below with reference to FIG. 2).This enables the controller 110 to determine whether the robotic worktool 100 is inside or outside an area enclosed by a boundary wire.

The controller 110 is connected to the motors 150 for controlling thepropulsion of the robotic work tool 100 which enables the robotic worktool 100 to service an enclosed area without leaving the area.

The robotic work tool 100 also comprises a work tool 160, which may be agrass cutting device, such as a rotating blade 160 driven by a cuttermotor 165. The cutter motor 165 is connected to the controller 110 whichenables the controller 110 to control the operation of the cutter motor165. The controller is also configured to determine the load exerted onthe rotating blade, by for example measure the power delivered to thecutter motor 165 or by measuring the axle torque exerted by the rotatingblade. The robotic work tool 100 is, in one embodiment, a roboticlawnmower.

The robotic tool may be powered by an electric motor 150 or a combustionengine 150, or a combination of the two. Below will be given a shortdescription of both such systems.

In the event that the robotic work tool is powered by a combustionengine 150, the robotic work tool 100 also has a fuel tank 180 forproviding fuel to the a-combustion engine 150 driving the wheels andpossibly the cutter 160. Alternatively, the fuel tank 180 also providesfuel to a cutter engine 165. Connected to the fuel tank 180 is a fuelintake adapted to establish a servicing connection with a correspondingmating connector (referenced 230 in FIG. 2) on a service station(referenced 210 in FIG. 2) for receiving fuel from service station(referenced 210 in FIG. 2). In the event that the robotic work tool ispowered by an electric motor 150, the robotic work tool 100 also has (atleast) one battery 180 for providing power to the motors 150 and thecutter motor 165. Connected to the battery 180 is two chargingconnectors, such as charging plates or charging rails 185 adapted toestablish an electrical connection with a corresponding mating chargingconnector (referenced 230 in FIG. 2) on a charging station (referenced210 in FIG. 2) for receiving a charging current from a charger(referenced 220 in FIG. 2) of the charging station (referenced 210 inFIG. 2). In one embodiment the charging connectors 185 are adapted toestablish the electrical contact by establishing physical contact whichis maintained through a biased member, such as by a spring or aninherent resilience of a flexible material being used as the chargingconnectors (230) of the charging station (210).

The charging connectors 185 are arranged on an upper portion of therobotic work tool 100 so that they are accessible from above. In oneembodiment the charging connectors 185 are arranged on the upside of therobotic work tool 100. The charging connectors 185 are furthermorearranged on one side of the robotic work tool 100 which enables asupporting member arranged to carry corresponding charging connectors(such as a support structure referenced 270 in FIG. 2) to only extendover a portion of a side of the robotic work tool 100. In this contextthe one side of the robotic work tool 100 is in relation to an imaginaryhalfway line across the width of the robotic work tool 100 seen in adirection of movement of the robotic work tool 100, i.e. a left side ora right side. The charging connectors 185 are arranged on one side ofthe robotic work tool with respect to an imaginary halfway line goingthrough the robotic work tool parallel to a direction of movement of therobotic work tool 100.

In one embodiment the robotic work tool 100 is of an articulatedtwo-part model as is shown in FIG. 2. It should be noted however, thatthe teachings herein are also possible for one-part models and other twopart models.

FIG. 2 shows a schematic view of a robotic working tool system 200comprising a charging station 210 and a boundary wire 250 arranged toenclose a working area 205, the working area 205 not necessarily being apart of the robot system 200.

The robotic work tool 100 of FIG. 2 is of a two-part model having afirst operating part 100A comprising operating means 160. In the exampleof FIG. 2, the robotic work tool 100 being a robotic lawnmower, theoperating part 100A comprises two cutting blades 160. It should be notedthat, in one embodiment, the operating part 100A may be interchangeable.This allows for using the same robotic work tool 100 for differentoperations. The robotic work tool 100 also has a second driving part100B, which, in the example of FIG. 2, comprises the driving means(electrical motor) and batteries (not shown). In the example of FIG. 2,the charging connectors 185 are arranged on the second part 100B of therobotic work tool 100 so that they are easily connected to the batteries(not shown).

The charging station 210 has a charger 220 coupled to, in thisembodiment, two mating charging connectors 230. The mating chargingconnectors 230 are arranged to co-operate with corresponding chargingconnectors 185 of the robotic work tool 100 for charging the battery 180of the robotic work tool 100. The mating charging connectors 230 of thecharging station are arranged on a support structure 270 which isarranged to rise above the robotic work tool 100 as the robotic worktool 100 docks in the charging station. In this manner the matingcharging connectors 230 of the charging station 210 may establishelectrical contact with the corresponding charging connectors 185 of therobotic work tool 100 from above.

By establishing the connection from above many advantages are providedfor, one being enabling a drive-through charging (or servicing) systemfor the robotic work tool 100 as there is no longer a wall or otherstructure in front of the robotic work tool 100 holding the chargingconnectors as in many prior art systems where a robotic work tool 100drives up to a charging station and presses against it using motorforce. The clever charging connector arrangement 230 disclosed hereinenables a secure connection without having to exert such drivingpressure.

By using a drive through charging station the lawn will be cut moreevenly around the charging station 210 avoiding aesthetically unpleasingpatterns in the lawn. Using a drive-through servicing station,especially one that a robotic work tool can enter from either direction,enables the robotic work tool to more easily find the charging stationand enter it without repeated and excessive operation (such as grasscutting) in one and the same area (such as the entrance to the chargingstation).

Furthermore, by establishing the connection from above the protectionfor the connectors is provided for by the support structure carrying theconnectors. The support structure can be designed to provide shelteragainst rain or other environmental factors, for example by simpleproviding the structure with a roof or other cover. Also, as thecharging connectors are placed at an upper side, they will be lesssubjected to debris, dirt and waste products (such as cut grass).

Furthermore, drive-in charging systems, such as in the prior art,generally require comparatively large structures in order to provideprotective shelter for the charging connectors, which becomes a problem,especially for larger robotic work tools as the protective shelter willincrease in size according to the size of the robotic work tool, makingthe resulting large charging station difficult to transport and toinstall as has been discussed in the background section. This will bediscussed in greater detail in the embodiments below.

To enable a reduced size of the charging station, the chargingconnectors 185 of the robotic work tool and the corresponding matingcharging connectors 230 of the charging station 210 are arranged inseries—and not in parallel—with reference to a movement direction of arobotic work tool entering the charging station. This allows for acharging station to be made smaller as the support structure 270 of thecharging station (making up the protective cover for the chargingcontacts) only need to extend over the two charging contacts. Byarranging the mating charging connectors 230 in series and by enabling adrive-through operation, the support structure 270 may only need toextend partially over one side of the robotic work tool 100 (whendocked). This significantly reduces the size of the charging stationwhich enables the charging station 210, and especially the supportstructure 270, to be made in a robust design suitable for outdoor use,without making the charging station 210 unsuitable for easy transport.

Drive-in charging systems are also unsuitable for use with some roboticwork tools, for example an articulated two-part model not havingadvanced steering capabilities, as they may be unable to reverse out ofthe charging station, depending on the design and allocation of thedriving means of the robotic work tool. This will also be discussed ingreater detail in the embodiments below

The charging station 210 also has, or may be coupled to, a signalgenerator 240 for providing a control signal (not shown) to betransmitted through the boundary wire 250. The control signal preferablycomprises a number of periodic current pulses. As is known in the art,the current pulses will generate a magnetic field around the boundarywire 250 which the sensors 170 of the robotic work tool 100 will detect.As the robotic work tool 100 (or more accurately, the sensor 170)crosses the boundary wire 250 the direction of the magnetic field willchange. The robotic work tool 100 will thus be able to determine thatthe boundary wire has been crossed. The use of more than one sensor 170enables the controller 110 of the robotic work tool 100 to determine howthe robotic work tool 100 is aligned with relation to the boundary wire250 by comparing the sensor signals received from each sensor 170. Thisenables the robot to follow the boundary wire 250, for example whenreturning to the charging station 210 for charging.

Traditionally, the charging station 210 may also have a guide cable 260for enabling the robot to find the entrance of the charging station 210.In one embodiment the guide cable 260 is formed by a loop of theboundary wire 250. The use of a drive-through servicing station makes itpossible for the robotic work tool to find its way to the servicingstation without a guide cable, y simply arranging the charging stationin line with the boundary cable.

It should be noted that other means of creating a boundary of the workarea and means for detecting such a boundary, as well as other means offinding and navigating to and into the service station are possible andshould be seen as to be covered in this application. The means disclosedabove are but one example of how such a robotic work tool may beimplemented.

FIG. 3 shows a schematic view of a robotic work tool system, such as therobotic work tool system 200 of FIG. 2. A robotic work tool 100 isdocked in a charging station 210. The docking station 210 has a supportstructure extending (at least) partially over the robotic work tool 100.The support structure 270 is arranged to carry two mating chargingconnectors (not shown in FIG. 3, but shown in detail in FIGS. 4 and 5)for cooperation with corresponding charging connectors on the roboticwork tool (not shown in FIG. 3, but shown in detail in FIGS. 4 and 5).

As can be seen in FIG. 3, the drive-through concept for the chargingstation 210 enables for a small, yet sturdy design, especially for thesupport structure 270 carrying the mating charging connectors. Byarranging the corresponding charging connectors on one side of an upperside of the robotic work tool, and possibly also in series, the supportstructure need only be of a relatively small size irrespective of inwhich part (referenced 100A and 100B in FIG. 2) of the robotic work tool100 that the corresponding charging connectors are arranged.

For example, using a traditional drive-in charging station, a supportmember carrying the charging connectors would need to reach acrosssubstantially the entire length of the robotic work tool 100 to reachcharging connectors arranged on the rear part of the robotic work tool100. Alternatively, charging connectors may need to be placed in theoperating part (100A) of the robotic work tool 100 in order to enablecharging in a drive-in charging station as in the prior art. However,this would make the operating part (100A) difficult to interchange asthe charging connectors would require disconnecting and reconnecting.Furthermore, one prior art charging station solution of having acharging connector on a side of the robotic work tool is especiallyprone to wear and tear in that the charging connector has to extend at alevel where it is subjected to debris and waste and is also sensitive tosideways collision damage. These problems and others are solved by arobotic work tool system 200 as in FIGS. 3 and 4.

The support structure 270 is arranged to provide protective cover forthe parts that are sensitive and/or vulnerable, such as the chargingconnectors (referenced 230 in FIG. 2), to protect from rain and otherenvironmental factors, by extending around the charging connectors. Asonly the charging connectors need be protected, the support structure270 need not be made larger than to extend around the chargingconnectors, and if they are placed on one side of the robotic work tool100, the support structure can be made comparatively small.

As has been mentioned in the above, the comparatively small size of thesupport structure 270 enables for maintaining a low weight, while stillallowing the support structure to be sturdy and robust to protectagainst external force. For example, the support structure 270 may bedesigned to be able to support the weight of a sitting person enabling acare taker to use the charging station as a resting place withoutrisking damaging the charging station 210.

FIG. 4 shows an enlarged sectional schematic view of a robotic work toolsystem 200, as in FIG. 3. The charging connectors 185 of the roboticwork tool 100 are arranged in series, with relation to a direction ofmovement of the robotic work tool 100. Corresponding mating chargingconnectors 230 of the charging station 210 are arranged to extend fromthe support structure 270 through each a lever arrangement 235. In theexample embodiment of FIG. 4, the lever arrangement 235 is arranged tomove in a direction substantially parallel to the direction of therobotic work tool's 100 movement as well as in a movement up and down.

The movement in the direction of the robotic work tool's 100 movementallows for the up/down movement to be smooth and with as little frictionas possible as the charging connectors 185 of the robotic work tool 100simply lifts the lever arrangement 235 to a suitable height by movingthe mating charging connector 230 forwards which simultaneously movesthe mating charging connector 230 upwards.

The movement up and down allows for variations in height of the roboticwork tool 100 to be charged. The movement up/down also allows forestablishing a proper contact between the corresponding chargingconnectors 185 and the mating charging connectors 230. It also enablesfor providing a substantially constant contact pressure, regardless ofthe height of the robotic work tool, and the arrangement is thussuitable for use with different models.

In one embodiment the mating charging connectors 230 of the chargingstation 210 are implemented as a collector shoe gear arrangement.

In one embodiment the lever arrangements 235 are biased downwards bytheir own weight to ensure a proper contact is established between thecorresponding charging connectors.

In one embodiment, as in the example of FIG. 4, the lever arrangements235 are spring-biased, for example through a spring 245, to ensure thatan improved contact is established between the charging contacts 185 ofthe robotic work tool 100 and the charging contacts 230 of the chargingstation 210.

By applying a biasing force to the lever arrangement 235, the connectors230 and 185 are brought into better contact with each other.Furthermore, by being pressed against each other the connectors 230 and185 clean each other's surfaces upon contact by scraping against eachother, thereby removing cut grass, leaves and other debris commonlyfound in a garden that may have clung to either of the mating chargingconnectors 230 or 185. This is also beneficial for preventing erosion oneither of the connectors 185 and 230.

FIG. 5 shows an alternative embodiment of a charging station 210,wherein the lever arrangement 235 is of a scissor-like construction. Theconstruction may be implemented as a (inverted) pantograph. This allowsfor accepting a robotic work tool 100 to be charged from eitherdirection. The lever arrangement 235 of FIG. 4 is best used to allow arobotic work tool 100 to enter from one side, whereas the leverarrangement 235 of FIG. 5 allows a robotic work tool 100 to enter fromeither direction. The lever arrangement 235 of FIG. 5 also folds awaynicely in case of a collision. The lever arrangement of FIG. 4 may alsobe used in a system that allows for entry in either direction, but thedimensions of the lever arrangement must be better adapted to the heightof the robotic work tool so that no unnecessary collision forces areexerted upon contact.

As can be seen in FIG. 5, the mating charging connector 230 may compriseon insulating member 232 carrying two sliding contacts (231).Alternatively, the mating charging connector may be comprised of twoseparate charging connectors, as in FIGS. 4 and 6.

FIG. 6 shows a detailed view of a robotic work tool system 200 as inFIGS. 2, 3, 4 and 5 emphasizing on the charging connectors 185 of therobotic work tool 100 and the corresponding mating charging connectors230 of the charging station 210.

Even though FIG. 6, shows a lever arrangement as in FIGS. 3 and 4, itshould be noted that the same type of connectors 230 may be used with alever arrangement 235 as in FIG. 5.

In the embodiment of FIG. 6, the mating charging connector 230 of thecharging station comprises a sliding contact 235. In one embodiment thesliding contact comprises a collector shoe gear. And, the chargingcontact 185 of the robotic work tool 100 is a connector rail 185.

In one embodiment the collector shoe gear is substantially wider thanthe connector rail 185. This allows for discrepancy and variance in theposition of the robotic work tool 100 with respect to the chargingstation 210 and also placement of the connector rail(s) 185 on therobotic work tool 100. The charging station may thus be used withdifferent types of robotic work tools 100 and also allow for smallererrors in navigation.

In the example of FIG. 6, the connector rail(s) 185 are arranged on arail support 187 having a front slanting portion 187A. The frontslanting portion 187A enables a smoother directed entry into thecharging station 210 as also the rail support 187 assists with raising acollector shoe gear, should the collector shoe gear be at a level lowerthan the connector rail(s) 185 as the robotic work tool 100 enters thecharging station 210.

This also allows for slight deviations in robotic work tool entry anglesand robotic work tool heights. It also protects the sliding contacts andthe hull of the robotic work tool 100 from collision damage.

In one embodiment the rail support 187 is also arranged to have slantingsides 187B. This enables electrical contact to be established even ifthe robotic work tool is entering the charging station at a leaningangle.

In one embodiment the driving part 100B of the robotic work tool 100comprises a chassis (not explicitly shown) and a hull 195 covering thechassis and the connector rail 187 is arranged on the chassis of therobotic work tool 100 to protrude through a corresponding opening in thehull. The opening in the hull is clearly visible in FIG. 5 andreferenced 190. This allows for an easier assembly, disassembly andreassembly of the robot as no connector wires are needed between theupper hull and the covered chassis. The hull 190 can thus simply beremoved and replaced without the need for disconnecting and reconnectingany wires.

The collector shoe gear arrangement for the connector 230 comprises asliding shoe contact 231 which is arranged to establish contact with thecorresponding charging connector rail 185 of the robotic work tool 100.The sliding shoe contact 231 is arranged to be carried on an insulatingmember 232 insulating the sliding shoe contact 231 from the leverarrangement 235.

The sliding shoe contact is arranged to be angled on the face 232meeting the connector rail 185 as the robotic work tool 100 enters thecharging station 210. Furthermore, the sliding shoe may be movablyarranged to the insulating member 232 (or, alternatively, the insulatingmember 232 is movably arranged on the lever arrangement) to allowmovement of the sliding shoe contact upon contact with the connectorrail 185. This reduces the friction and impact between the charging rail185 and the sliding shoe contact 231 as the robotic work tool 100 entersthe charging station 210. This arrangement also protects the connectors185 and 230 from collision damage.

In one embodiment (as shown in the figures) the insulating member 232 isarranged with corresponding angled portions.

In one embodiment, as in FIG. 6, the sliding contact 231 is also angledon the face leaving the charging rail 185 as the robotic work tool 100exits the charging station 210. This reduces the wear and tear betweenthe charging connectors 185 and 230. This also allows for multipledirection entry as in the embodiment of FIG. 5.

In one embodiment the sliding contact 231 is arranged with a partitionwhich effectively shapes the sliding contact 231 into at least twocontact surfaces 233. In one embodiment, as in FIG. 6, the contactsurfaces are shaped to be pointed. The use of multiple contact pointsreduces eroding and also reduces the risk of electrical discharge. Thepointed shape reduces the contact surface of the sliding contact 231which increases the pressure in the contact point 233 which improves theelectrical connection between the connectors.

The sliding contact 231 is thus formed to have at least one wing 234 andat least two contact points 233 separated by a partition 236. Due to theangling of the wings 234 abutting the contact points 233 the contactpoints 233 are arranged to be pointed and have a small contact surface.

The arrangement of multiple contact points and that are shaped toincrease the contact pressure in the contact points enable for highcharging currents to be used (around 10 A, and above 2 A) and thecharging station can thus be used for larger and possibly morecomplicated robotic work tools 100 that the charging stations of theprior art would not be able to provide a sufficient charging current to.

Furthermore, in one embodiment with two connector rails 185, theconnector rails 185 are arranged spaced apart on the same rail support187. Arranged in between the two connector rails 185 may be aninsulating material. The connector rails 185 should be spaced apart adistance wider than the length of a corresponding collector shoepartition 236 to ensure that the charging system is not short circuited.In one embodiment the collector shoe partition 236 has a width of 18 mmand the connector rails are spaced apart 26 mm. In one embodiment theconnector rails 185 are each 94.5 mm long and the collector shoes arespaced apart 120 mm.

In one embodiment the sliding contact 231 is rotatably connected to thecollector shoe arrangement (as has been disclosed in the above). Thisenables for the sliding contact 231 to move and adapt to a connectorrail 185 that hits the collector shoe gear at an angle other than apreferred angle. This reduces the wear and tear on the collector shoearrangement and prolongs the effective life time of the chargingcontacts.

Suitable dimensions of the rails 185, the rail support 187, the leversystem holding the charging connectors 230 and the charging connectors230 depend on many design variables, such as the docking speed of therobotic work tool 100, the charging current and the accuracy of thepositioning of the robotic work tool 100. It also depends on the exactmodel of the robotic work tool to be charged. Above has been given someexamples of dimensions, but it should be understood that the dimensionsmay vary between different systems.

Rolling wheels would for example be more prone to eroding and electricaldischarge. Especially the rolling wheels would be more sensitive to wearand tear especially in the wheel bearings. Also, they would be sensitiveto debris and waste and a wheel partially covered in waste may not beable to establish an electrical connection if the covered portion of thewheel is in contact with a corresponding connector. The same applies tocharging connectors which are pressed against each other simply by theweight of the robotic work tool standing parked in the charging station.Furthermore a system in which the robotic work tool 100 continues topress against the mating charging connectors 230 of the charging stationis also prone to eroding and electrical discharge caused by the repeatedminute collisions that arise in such a system.

In one embodiment the charging station is a service station forrefueling a robotic work tool operating using a combustion engine (or acombustion engine in combination with an electric motor). The chargingor service station may then be arranged with one mating serviceconnector 230 which is arranged to mate with a fuel intake. The matingservice connector 230 may be biased using a pantograph structure such asin FIG. 5 or a lever structure such as in FIG. 4 to enter a fuel intake185 as the fuel intake 185 is positioned under the mating serviceconnector 230. FIG. 7 shows a schematic example of such a servicestation 210. Such a service station may benefit from may of theadvantages listed and discussed above for a service station being acharging station. For example, the position of the mating connector 230enables for a drive through arrangement. The fuel inlet 185 may beprotected by an extending structure. The fuel inlet may also be arrangedwith a guiding surface for guiding the mating connector 230 into thefuel inlet 185. The mating connector 230 may be spring biased toautomatically be inserted into the fuel inlet 185 upon mating. Themating connector may be arranged as a (flexible) pipe for protrudinginto the fuel inlet 185 upon mating.

References to ‘computer-readable storage medium’, ‘computer programproduct’, ‘tangibly embodied computer program’ etc. or a ‘controller’,‘computer’, ‘processor’ etc. should be understood to encompass not onlycomputers having different architectures such as single/multi-processorarchitectures and sequential/parallel architectures but also specializedcircuits such as field-programmable gate arrays (FPGA), applicationspecific circuits (ASIC), signal processing devices and other devices.References to computer program, instructions, code etc. should beunderstood to encompass software for a programmable processor orfirmware such as, for example, the programmable content of a hardwaredevice whether instructions for a processor, or configuration settingsfor a fixed-function device, gate array or programmable logic deviceetc.

One benefit of the teachings herein is that the charging station isarranged to manage large charging currents. Another advantage is thatthe drive-through design reduces the tracks and lawn-wear in the areasurrounding the charging station 210. Another benefit is that thecharging station is enabled to allow for variations in height due todifferent robotic work tool models, wear, and dirt. The shape of thesliding contact brings about the benefit that the contact between therobotic work tool and the charging station is guided. And anotherbenefit is that the arrangement reduces the need for cabling betweendifferent parts of the robotic work tool making assembly, disassemblyand reassembly easier.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

The invention claimed is:
 1. A robotic lawnmower system, comprising acharging station and a robotic lawnmower, said robotic lawnmowercomprising a charging connector arranged on an upper side of the roboticlawnmower and said charging station comprising: a mating chargingconnector; and a supporting structure arranged to carry said matingcharging connector and to extend over said robotic lawnmower as therobotic lawnmower enters a first end of the charging station forestablishing energy transfer contact between the charging connector ofthe robotic lawnmower and the mating charging connector of the chargingstation from above, wherein said supporting structure is configured toallow the robotic lawnmower to select to exit between a second end ofthe charging station by driving through the charging station and thefirst end of the charging station by reversing from the chargingstation.
 2. The robotic lawnmower system according to claim 1, whereinthe mating charging connector of the charging station is arranged on alever arrangement, said mating charging connector being a collector shoegear.
 3. The robotic lawnmower system according to claim 2, wherein thecollector shoe gear is arranged with an angled portion on a face of themating charging connector facing the robotic lawnmower as the roboticlawnmower enters the charging station.
 4. The robotic lawnmower systemaccording to claim 3, wherein the collector shoe gear is arranged on aninsulating member also being arranged with an angled portion on a faceof the insulating member facing the robotic lawnmower as the roboticlawnmower enters the charging station.
 5. The robotic lawnmower systemaccording to claim 2, wherein the collector shoe gear is arranged with apartition to provide at least two contact points.
 6. The roboticlawnmower system according to claim 5, wherein the contact points arepointed.
 7. The robotic lawnmower system according to claim 2, whereinthe lever arrangement is of a pantograph design.
 8. The roboticlawnmower system according to claim 2, wherein the lever arrangement isarranged to move forwards and upwards as the robotic lawnmower entersthe charging station to make contact between the mating chargingconnector of the charging station and the charging connector of therobotic lawnmower.
 9. The robotic lawnmower system according to claim 1,wherein the robotic lawnmower comprises multiple charging connectorsthat are arranged in series with regard to a direction of movement ofthe robotic lawnmower.
 10. The robotic lawnmower system according toclaim 1, wherein the charging connector of the robotic lawnmower isarranged as a charging rail arranged to mate with a sliding chargingconnector of the charging station.
 11. The robotic lawnmower systemaccording to claim 10, wherein the charging rail is arranged on acharging support having a slanting portion for guiding the matingcharging connector of the charging station as the robotic lawnmowerenters the charging station.
 12. The robotic lawnmower system accordingto claim 10, wherein the charging rail is arranged on a charging supporthaving a slanting side portion for allowing a variation of tilt of therobotic lawnmower as the robotic lawnmower enters the charging station.13. The robotic lawnmower system according to claim 10, wherein thecharging rail is arranged to protrude through an opening in a hull ofsaid robotic lawnmower.
 14. The robotic lawnmower system according toclaim 1, wherein the charging connector of the robotic lawnmower isarranged on one side of the upper side of the robotic lawnmower withregards to the direction of movement of the robotic lawnmower.
 15. Therobotic lawnmower system according to claim 1, wherein the chargingconnector of the charging station is biased by a spring.
 16. The roboticlawnmower system according to claim 1, wherein the charging station isarranged to supply a charging current exceeding 2 A.
 17. A roboticlawnmower system, comprising: a service station; and a roboticlawnmower, said robotic lawnmower comprising at least one correspondingconnector arranged on an upper side of the robotic lawnmower, whereinsaid service station comprises at least one mating connector and asupporting structure arranged to carry said at least one matingconnector and to extend over said robotic lawnmower as the roboticlawnmower enters a first end of the service station for establishing anenergy transfer contact between the at least one corresponding connectorof the robotic lawnmower and the at least one mating connector of theservice station from above, wherein said supporting structure isconfigured to allow the robotic lawnmower to select to exit between asecond end of the service station by driving through the chargingstation and the first end of the charging station by reversing from thecharging station, and wherein said energy transfer is a transfer of fueland said at least one corresponding connector is a fuel inlet.